The most devastating aspect of a shock, such as an earthquake, is the rupture of natural gas lines and the subsequent fires and explosions. Even a small leak in a gas line can accumulate enough gas in a building to cause a serious explosion if ignited. A major portion of the damage following the San Francisco earthquake of 1906 and more recently, the Los Angeles quake of 1993 resulted from the fires following the tremors rather than the structural damage of the shock. Other natural disasters such as tornadoes and hurricanes can severely damage the integrity of natural gas lines.
Similarly, in war zones such as the former Yugoslavia, it would be desirable to be able to shut down gas lines when under bomb or shell attack.
Recognizing the need for a shut-off valve mechanism for natural gas lines, various devices have been developed over the past twenty years. Several of these devices are intricate, expensive to manufacture and focus primarily on industrial as opposed to household or consumer use. Others simply do not work.
U.S. Pat. No. 3,965,917 to Speck discloses an earthquake valve in which a shock causes two interlocked cylinders to become misaligned, which in turn causes a latching means to release a valve to close the pipe.
U.S. Pat. No. 4,336,818 to Dauvergne discloses another earthquake valve. In this case, a shock to the valve causes the metal ball to be horizontally dislodged from its pedestal, which allows a flap closure to drop closing the valve over the gas line.
U.S. Pat. No. 5,143,110 to Simpson discloses another arrangement in which the series of balls moves up the sides of the valve under shock, allowing a piston to drop into the closed position.
U.S. Pat. No. 4,915,122 to Ikegaya et al. Provides a device in which a shock to the valve causes a ball to roll off a pedestal, forcing a cylindrical tube downwardly to release a latching mechanism and causing the valve to rotate downwardly into a closed position.
Each of these devices comprise a multitude of interconnecting parts and would be expensive to manufacture and sell, particularly for the household and consumer market. In addition, the installation and use of these devices is not practical at the consumer level.
Although the Simpson patent claims to provide an earthquake sensing mechanism that is omnidirectional in its sensitivity, none of these devices allow for a simple means of sensitivity adjustment. In addition and equally importantly, none of these devices can be easily reset by a non-technical person.
It is an object of a present invention to obviate and mitigate the above disadvantages.